There is nothing unimplemented here. We produce the correct error.

Test: dEQP-VK.api.device_init.create_device_unsupported_features
Change-Id: I663fa376bda0752e1c17992be29aac7bd1cbecda
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/31028Reviewed-by: Ben Clayton <bclayton@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Chris Forbes <chrisforbes@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>